This invention relates in general to portable power tool apparata which are powered by a direct current power source which powers related equipment. More particularly the present invention relates to a portable weld grinding apparatus which is powered by a direct current power source which powers related welding equipment.
Portable power tools are frequently used at construction sites and particularly in high-rise construction. These portable power tools are either powered by alternating current power sources or by direct current batteries. In high-rise construction alternating current powered tools create a problem because alternating current power lines have to be strung up from the ground up to the height at which the power tools are being used. Since modern high-rise construction tends to involve very tall buildings, the length and plurality of alternating current power lines becomes excessive if the power tools are to be used in the upper areas of the structure.
Battery powered tools are a problem because the batteries have to be charged or recharged frequently and this interrupts construction causing downtime and increasing costs. Further, when a worker is in the midst of an operation such as, grinding a weld, he needs a reliable tool, and battery powered tools can run out of power at inappropriate times.
On current high-rise buildings one of the power tools that is most often used is a portable weld grinder. Due to the large amounts of structural metal that are used in high-rise construction, a great amount of welding is required. Since welding work also includes grinding down welds, the use of a portable weld grinder plays an important role. As welds are made they have to be continuously ground so that the welder can insure that the weld does not have any imperfections in it. By grinding the weld down as he builds the weld up the welder can continuously check for internal flaws and contamination. Thus the welder needs the capability to easily and quickly switch from welding to grinding.
A great deal of the welding that is done in high rise construction is electric arc welding which requires a direct current power source. Usually one direct current main power cable is strung up to the area where the welding is done and is connected to a main or central DC power unit. From this unit a plurality of direct current branch cables are run to the various welding sites. These direct current branch cables are used in the electric arc welding. In present arrangements a plurality of alternating current electrical cables have to be strung so as to power the alternating current weld grinders which are used to grind the welds. These alternating current electrical cables are an inconvenience and create a potential hazard at the construction site. It would be an improvement to these present arrangements to have power tools which operate on the power source that is used for the welding so that separate alternating current power lines do not have to be strung throughout the high-rise just for the power tools. This improvement will reduce the hazard and make the welding process much more convenient and efficient.
It would thus be beneficial to have power tools which would operate off of this direct current power source so that only one cable need be strung up to these high reaches of the high-rise construction. Ideally this cable would be the direct current power cable which also powers the electric arc welding. Once a layer of weld is applied, the welding device could be unhooked from the cable and then the power tools which are designed to operate on this direct current power source could be attached and subsequently used. There is less danger by this improved approach because the problems created by having many power cables strung about the structure are eliminated.
Unlike present arrangements, the present invention provides specifically for a portable weld grinding apparatus which takes advantage of the direct current power source which powers the related welding equipment. This apparatus is easily attached to the direct current cable which powers the welding equipment so that an operator can easily create a weld and then switch over to the weld grinding apparatus so as to grind the weld. The direct current power source which powers the related welding equipment can also be used to power an entire line of power tools which are used at construction sites. These power tools can be set up so as to run on this power source so that there is no need to string alternating current cables into the higher reaches of the construction site. As a result of the present invention only one cable need be strung up to the construction site and this cable can be the direct current cable which powers the related welding equipment.
The prior patented devices known to the inventor do not disclose any power tools which would be suitable for use with the direct current power source that powers the related welding equipment at a construction site. The following listed patents are believed to be representative of such prior patented devices:
______________________________________ Patent Number Patentee ______________________________________ 3,566,546 Lindmark 3,823,455 McIlrath et al. 3,274,476 Wildum 2,867,039 Zach 2,808,521 K-F Scal 2,719,946 Riley 1,085,840 Apgar ______________________________________
Lindmark shows an apparatus for grinding welded rail, but the device is by no means portable and would not be useable at a construction site in a hand held fashion. McIlrath shows a rail polishing machine. Wildum merely shows an article carrying belt. Zach shows a face shaving apparatus. K-F Scal shows a direct current power supply system. Riley shows a multiple phase transformer and dry disc rectifier assembly for resistance welding machines, and the like, as an example of the types of power sources which are used with electrical arc welding. Apgar shows a portable grinder, but this grinder is not hand held and would not be as portable as the power tool of the present invention nor is it specifically designed to be used with the direct current power source which powers related welding equipment at a construction site. These patents do not show any devices or apparatus which could be used as the present invention can be used with the power source which powers related welding equipment at a construction site.